for bizgram and most stores, only buy when u have done your homework...

bizgram usually has competitive prices and has stocks for the items on its updated pricelist... i only buy parts from here after comparing prices across a few stores (fuwell, bizgram, dell, pc themes, videopro/best price) videopro and best price is essentially same shop, same pricelist..

videopro will usually show a cheaper price on pricelist abd has alot of items ob its pricelist but will also frequently tell u no stock or price changed, u want or not.. cs quality varies alot at videopro..

pc themes, vpro, bizgram r the three shops i would hunt for parts but aleays check latest prices from fuwell bell etc.. fuwell usually more expansive for parts..

all shops sell diff parts at different costs.. ie some shop ram is cheaper, some hdd is cheaper, some gfx is cheaper.. etc.. u need to do your home work before buying anything at all.

now.. upgrading a bundle system or buying a bundle system w/o comparing actual bundle price is very naive and careless. bundle system upgrades usually is more expansive than u DIY select the parts!! unless u r looking at office PC at 300-400 range when u already own OS, else always go for DIY select parts.

never buy bundle system for gaming unless u have checked psu / ram / mb used and compared prices.. if u buy a bundle system, upgrade and paid already.. in sg law is considered u agreed to the price tag for the goods/services received.. upgrading ram is usually stupid on a bundle system as usually the price top up u can buy a better ram.

with ur budget, 9xx i dunno how u end up with ur final system as only the mb/cpu looks ok, no comment on its price tag as i dun own any 1555 board/cpu.
for HDD, i would go for black 1TB $2xx
ram 16GB - 2nd hand $100
casing - 2nd hand usb3 $50-70
psu - seasonic X-660 660W FULL MODULAR 80+ GOLD @ $165
gfx - 2nd hand gtx 5xx $250 - 1- 2yr++ warranty
addup to $7xx - u can buy M12 instead and save $30-$50 to keep within budget. hdd go green and save $40-60 ish.. always room to play around with

with enof $$$ left or top up minimal for usb3 board with i5 cpu.. u can even save gfx $$ with on board gfx.. and 500GB is enof for most ppl unless u download alot of craps